It was even used in the [[Sega MegaDrive]] as the sound CPU and in the [[Commodore C128]] as a secondary processor in order to achieve [[CP/M]] compatibility. Similarly, the Acorn Z80 Second Processor expansion for the [[BBC Micro]] enables [[CP/M]] compatibility.
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== History ==
In the early 1970s, Intel developed the 8080, one of the first widely used microprocessors. However, a group of engineers, led by Federico Faggin, who had worked on the 8080, left Intel to start their own company called Zilog in 1974.
At Zilog, Faggin and his team wanted to create an improved version of the 8080 that would be more efficient, flexible, and easier to use. This led to the development of the Z80, which was designed to be both backward-compatible with the 8080 and more powerful. This compatibility meant that any software written for the 8080 could run on the Z80, making it an attractive upgrade for manufacturers and developers.
The Z80 had several key improvements over the 8080. It featured more registers, a more complete instruction set and improved interrupt handling. It also had built-in memory refresh for dynamic RAM, that made it easier to build systems around it.
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The Z80 microprocessor is an 8-bit [[CPU]] with a 4-bit ALU and a 16-bit address bus capable of direct access to 64KB of memory space. The Z80 is a little-endian CPU, meaning it stores 16-bit values with the least significant byte first, followed by the most significant byte. It has a language of 252 root instructions and with the reserved 4 bytes as prefixes, access to an additional 308 instructions.
The Zilog Z80 is an upgraded version of the [[8080|Intel 8080]] and is fully compatible with it at the software level. It contains the seventy-eight 8080 opcodes as a subset to its language. The Z80 adds more registers, better instructions, faster performance, and improved interrupt handling, making it more powerful and efficient than the 8080.
While not in the same league as the Intel 80x86 or the [[Motorola 68000]] series, the Z80 is extremely useful for low cost control applications. One of the more useful features of the Z80 is the built-in refresh circuitry for ease of design with DRAMs.